Cut-out for incandescent lamps



NITED STATES PATENT OFFICE.

TURNER D. BOTTOME, OF NEYV YORK, N. -Y., ASSIGNOR TO JOHN B. TIBBITS, OFHOOSICK, NEll YORK.

CUT-OUT FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 414,792, dated November12, 1889.

Application filed Tune 25, 1889. Serial No. 315,566. (No model.)

To all whom it may concern.-

Be it known that I, TURNER D. BOTTOME, a citizen of the United States,and a resident of New York, in the county of New York and State of NewYork, have invented certain new and useful Improvements in a Cut-Out forIncandescent Lamps, of which the following is a specification.

This invention relates to an automatic method of cutting out rupturedincandescent electric lamps from alternating-series circuits.

The objects of the invention are to produce a simple, cheap, andeffective device for keeping a series incandescent lamp circuit 5 closedwhen a lamp on such a circuit becomes burned out or ruptured.

I obtain my objects by the mechanism ill ustrated in the accompanyingdrawings, which form a part of this specification;

Figure 1 illustrates a lamp complete in working order with the cut-out.

Fig. 2 is a diagram of the cut-out. P and N represent the lamp orfilament F terminals. 0 and d are the connections with the filament Fand the terminal wiresP and N of the lamp L. f A and B are loops, 0fcopper or other metallic wire, bent into the shape of the filament F,and are placed normally and preferably in a position just inside of thefilament F, Figs. 1 and 4. The distance between each other and from thefilament is about one-sixteenth to one-eighth of an inch; but I do notlimit myself to any particular distance of sep aration. In the drawingsthe distance shown may be slightly exaggerated, in order to more clearlyshow the relative positions of the filament and cut-out loops. As seenfrom the diagram, A connects with the terminal P at a point shown at 2',while B is similarly connected at j to N.

Fig. 3 shows a filament F combined with the cut-out loops A and B, butout in half, with the ends or edges presented to view.

Fig. 4 is a lamp complete that has been out out.

Therupture of the filament is shown at g, and the fusing-points of theloops A and B are shown fused together at h.

The operation of the cut-out may be explained as follows: The electriccircuit normally is through the terminals P and N and through thefilament F. A andB simply act as terminals adjunctive to P and N. Thefilament on becoming ruptured causes an arc to be formed at suchrupture. The distance may not be over one one-thousandth of an inch atfirst, but it quickly becomes greater. and increases in lengthsay toone-fourth of an inch-but the terminal or cut-out loops A and B are onlyone-sixteenth of an inch apart or so, and a similar distance from thefilament, or a total of three-sixteenths, more or less. A and B are bothat all points in the same close proximity to the filament F and tothemselves, so that when the distance between the points of the arcingfilament exceeds the total distance between the loops A and B and thefilament F the are on the filament transfers itself onto the loops A andB,

and the heat of the arc quickly fuses the metallic wires and the moltenbeads of metal soon come into contact and thereby close the electriccircuit at that point.

I am aware that it is generally known that a spark or that a current ofelectricity will not jump nor form an arc in a vacuum; but such factshold good only witha perfect vacuum. The commercial vacuum of anordinary incandescent lamp forms a better conductor by far forelectricity than air does, which fact is easily proved from theperformance of an ordinary Geissler tube.

Another example is the frequent destruction of an ordinaryone-hundred-bolt sixteencandle-power lamp by the current jumping acrossthe terminals inside the lamp, forming an are, which instantly meltsdown the platinum conducting-wires. This action often happens when theplatinum wires are nearly, if not quite, fully one-half an inch apart.This action more commonly happens when the filament in the lamp isnearly used up or disinte- IOO ing a long jump with a low clectro-motiveforce is the case of an ordinary electric-arc lamp, which may be startedup, not by first touching the carbon pencils together, as commonly thepractice, but by holding a candle or alcohol flame between the separatedcarbon terminals. In a short time the current will pass, forming a fullare. This isdue to the presence of minute particles of carbon, or evenvapor, which is detached by the heat of the flame placed between thecarbons. In my case the carbon filament, or a filament composed of ametal and carbon-such. as tungsten and carbon-on being ruptured isvolatilized, the vapor occupying the vacuum in the inclosed lamp. Thepresence of this good conducting vapor, together with the closeproximity of the cut-out loops A and B to each other and to the filamentF, makes the action quite certain above alluded tonamely, the jumping ofa low potential current causing the are from the ruptured filament totransfer to the metallic conductors A and B,

which eventually become fused together,

thereby closing the circuit.

I do not limit myself to any particular form of filament to which toapply the cut-out, because it can be placed and operated with any styleor shape filaments, the only necessary condition of success being tofollow the lines of the filament closely and to keep the distancesuniformly close.

I do not limit myself to simply applying the cut-out to lamps containingonly one filament, because it is equally applicable to lamps containingseveral filaments.

I am aware that cut-outs have been devised and used in which theterminals of the lamp were placed closely together, but sepa 'ated by athin stratum of either some high-resistance conducting mass or by anon-conductor, such as mica. In either case the operation of the cutoutdepends on an are being formed which eventually cuts out the lamp by theterminals becoming fused together. In the first case the circuit cannotbe broken, because it takes the path of the high-resistance body, whichsoon fails to be a high resistance and causes the lamp to beshort-circuited or cut out. other case the potential of the current mustbecome of such an electro-motive force as to enable the current topuncture the nonconducting medium and form an arc.

IVhat I claim as new and original is as follows:

1. An alternatingcurrent cut-out consisting of two metallic loopselectrically connected to the terminal wires of a filament and placed inclose proximity to each other and the filamentalong its entire length,each loop corresponding in shape to the said filament, substantially asshown and described.

2. An alternating-current cut-out consisting in an incandescent-lampfilament and two metallic loops of the same shape as the filament, oneloop being electrically connected to one and the other loop to the otherterminal of the filament, and all placed closely together, as shown, andfor the purpose d escribed.

Signed at NewYork, in the county of New York and State of New York, this15th day of Hay, A. D. 1889.

TURNER l). BO'PJOME.

Witnesses:

EMIL REINER, Louis H. Zocnna.

In the

